U.S. patent number 6,427,660 [Application Number 09/620,147] was granted by the patent office on 2002-08-06 for dual fuel compression ignition engine.
This patent grant is currently assigned to Ford Global Technologies, Inc.. Invention is credited to Jialin Yang.
United States Patent |
6,427,660 |
Yang |
August 6, 2002 |
Dual fuel compression ignition engine
Abstract
A compression ignition internal combustion engine 7 is provided.
The engine has at least one combustion chamber 10 having an air
inlet 14 and an exhaust outlet 26. A dual fuel injector is provided
having a mixing chamber 46 with an outlet fluidly connected with
the combustion chamber 10 via a first valve 54. A liquid fuel line
64 is provided for delivering liquid fuel to the mixing chamber 46.
The liquid fuel line 64 is connected to the mixing chamber 46 via a
second valve 60. A combustible gas line 56 is provided for
delivering compressed combustible gas to the mixing chamber 46.
Upon an opening of the first valve 54, the liquid fuel is brought
into the combustion chamber 10 by the compressed combustible
gas.
Inventors: |
Yang; Jialin (Canton, MI) |
Assignee: |
Ford Global Technologies, Inc.
(Dearborn, MI)
|
Family
ID: |
24484776 |
Appl.
No.: |
09/620,147 |
Filed: |
July 20, 2000 |
Current U.S.
Class: |
123/304; 123/526;
123/531 |
Current CPC
Class: |
F02D
19/081 (20130101); F02D 19/10 (20130101); F02D
19/0647 (20130101); F02B 7/06 (20130101); F02D
19/0605 (20130101); F02D 19/0694 (20130101); Y02T
10/30 (20130101); F02B 3/06 (20130101); Y02T
10/36 (20130101); F02M 43/00 (20130101); F02B
2201/06 (20130101) |
Current International
Class: |
F02D
19/00 (20060101); F02B 7/00 (20060101); F02B
7/06 (20060101); F02D 19/10 (20060101); F02B
3/06 (20060101); F02B 3/00 (20060101); F02M
21/02 (20060101); F02M 43/00 (20060101); F02M
043/00 () |
Field of
Search: |
;123/276G,304,526,299,531 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Argenbright; Tony M.
Assistant Examiner: Harris; Katrina B.
Attorney, Agent or Firm: Hanze; Carlos
Claims
I claim:
1. A compression ignition internal combustion engine comprising: at
least one combustion chamber having an air inlet and an exhaust
outlet; a reciprocating piston slidably mounted within said
combustion chamber; a dual fuel injector having a mixing chamber
with an outlet fluidly connected with said combustion chamber via a
first valve; a liquid fuel line delivering liquid fuel to said
mixing chamber, said liquid fuel line being connected to said
mixing chamber via a second valve; and a combustible gas line for
delivering compressed combustible gas to said mixing chamber to
bring said liquid fuel into said combustion chamber upon an opening
of said first valve.
2. A compression ignition internal combustion engine as described
in claim 1, wherein said combustible gas is compressed natural
gas.
3. A compression ignition internal combustion engine as described
in claim 1, wherein said liquid fuel is a diesel fuel.
4. A compression ignition internal combustion engine as described
in claim 1, wherein there is a pressure regulator which controls
the pressure of said combustible gas delivered to said mixing
chamber.
5. A compression ignition internal combustion engine as described
in claim 1, wherein said pressure of said combustible gas delivered
to said mixing chamber is between 15 and 45 bar.
6. A compression ignition internal combustion engine as described
in claim 1, wherein said liquid fuel is delivered to said mixing
chamber at a pressure under 50 bar.
7. A compression ignition internal combustion engine as described
in claim 1, wherein said liquid fuel is delivered to said mixing
chamber at a higher pressure than a pressure of said combustible
gas when said combustible gas is delivered to said mixing
chamber.
8. A compression ignition internal combustion engine comprising: at
least one combustion chamber having an air inlet and an exhaust
outlet; a reciprocating piston slidably mounted within said
combustion chamber; a dual fuel injector having a mixing chamber
with an outlet fluidly connected with said combustion chamber via a
first valve; a diesel fuel line for delivering diesel fuel to said
mixing chamber at a first pressure via a second valve; a compressed
combustible gas line for delivering compressed natural gas to said
mixing chamber, said compressed natural gas bringing out said
diesel fuel into said combustion chamber upon opening of said first
valve; and a pressure regulator for regulating the pressure of said
compressed natural gas delivered to said mixing chamber to a
pressure lower than said first pressure.
9. A method of operating a compression ignition internal combustion
engine having at least a first combustion chamber with an air inlet
and air outlet and said combustion chamber having a slidably
mounted reciprocating piston, said engine also having a dual fuel
injector with a mixing chamber with an outlet connected with said
combustion chamber via a first valve, said mixing chamber being
connected with a source of compressed combustible gas and said
mixing chamber being connected via a second valve with a source of
pressurized liquid fuel, said method comprising: opening said
second valve to deliver liquid fuel into said mixing chamber; and
opening said first valve to allow said compressed combustible gas
to bring out said liquid fuel into said combustion chamber.
10. A method of operating a compression ignition internal
combustion engine as described in claim 9, wherein said compressed
combustible gas bringing out said liquid fuel is compressed natural
gas.
11. A method of operating a compression ignition internal
combustion engine as described in claim 9, wherein said liquid fuel
delivered into said mixing chamber is a diesel fuel.
12. A method of operating a compression ignition internal
combustion engine as described in claim 9, having multiple
injections into said combustion chamber wherein a separate initial
injection of combustible gas is made into said mixing chamber by
opening said first valve before said opening of said second valve
to deliver liquid fuel into said mixing chamber.
13. A method of operating a compression ignition internal
combustion engine as described in claim 12, wherein said separate
initial injection of combustible gas into said combustion chamber
is during an intake stroke of said piston.
14. A method of operating a compression ignition internal
combustion engine as described in claim 13, wherein said separate
initial injection of combustible gas into said combustion chamber
can be selectively retarded based upon an operational condition of
said engine.
15. A method of operating a compression ignition internal
combustion engine as described in claim 14, wherein said engine
operational condition is a load on said engine.
16. A method of operating a compression ignition internal
combustion engine as described in claim 9, wherein said liquid fuel
is delivered into said mixing chamber at a higher pressure than a
pressure of said compressed natural gas.
17. A method of operating a compression ignition internal
combustion engine as described in claim 16, wherein said pressure
of said liquid fuel is under 50 bar.
18. A compression ignition internal combustion engine comprising:
at least one combustion chamber having an air inlet and an exhaust
outlet; a reciprocating piston slidably mounted within said
combustion chamber; a dual fuel injector having a mixing chamber
with an outlet fluidly connected with said combustion chamber; a
first valve for releasing into said combustion chamber contents of
said mixing chamber; a second valve for delivering a liquid fuel to
said mixing chamber; a third valve for delivering a compressed
combustible gas to said mixing chamber; and a fourth valve for
delivering compressed air to said mixing chamber.
19. A compression ignition internal combustion engine as described
in claim 18, wherein said compressed combustible gas powers an air
compressor supplying compressed air to said third valve.
20. A compression ignition internal combustion engine as described
in claim 18, wherein said third and fourth valves are provided by a
three-way valve that alternatively connects said mixing chamber
with said compressed combustible gas or said compressed air.
21. A method of operating a compression ignition internal
combustion engine having at least a first combustion chamber with
an air inlet and an air outlet, and said combustion chamber having
a slidably mounted reciprocating piston, said engine also having a
dual fuel injector with a mixing chamber with an outlet connected
with said combustion chamber via a first valve, said mixing chamber
being connected via a second valve with a source of pressurized
liquid fuel, said mixing chamber also being connected with a source
of compressed combustible gas via a third valve, said mixing
chamber also being connected with a source of compressed air by a
fourth valve, said operating method comprising: opening said first
and third valves to deliver compressed combustible gas to said
combustion chamber; opening said second valve to deliver liquid
fuel to said mixing chamber; opening said fourth and second valves
to deliver compressed air into said mixing chamber to bring said
liquid fuel into said combustion chamber.
22. A method of operating a compression ignition internal
combustion engine as described in claim 21, wherein said delivery
of said combustible gas into said mixing chamber is performed
during an intake stroke of said piston.
23. A method of operating a compression ignition internal
combustion engine as described in claim 21, wherein said timing of
the delivery of said combustible gas is based upon a load of said
engine to achieve a stratified charge within said combustion
cylinder.
Description
FIELD OF THE INVENTION
The field of the invention is that of dual fuel powered compression
ignition internal combustion engines. More particularly, the field
of the present invention is that of a diesel engine which can
alternatively or simultaneously be powered by compressed natural
gas and a petroleum or non petroleum liquid diesel fuel.
BACKGROUND OF THE INVENTION
To help clean up the environment, great strides have been made in
reducing the exhaust emissions of automotive vehicle engines. In a
further attempt to lower vehicle engine emissions, the use of
alternative fuels has been explored. An excellent example of such a
fuel is compressed natural gas (CNG). There has been much progress
in lowering emissions by using CNG, most notably in spark-ignited
internal combustion engines.
It is desirable to extend the use of CNG to compression ignition
engines such as diesel engines. However, CNG typically must be
compressed to far higher pressures than what typically occur in a
compression cycle of a conventional diesel engine before the CNG
will auto-ignite. Additionally, it is very hard to disperse a gas
within a compression chamber under pressurized conditions. Liquids
are easier to inject into a pressurized combustion chamber to
achieve disbursal of the fuel within the combustion chamber.
Accordingly, to utilize CNG, a small amount of diesel fuel is
typically added which auto-ignites at the conventional diesel
compression pressure. The ignited diesel fuel generates a
temperature spike within the combustion chamber which causes the
CNG to ignite.
Prior to the present invention, there have been various inventions
to allow the use of CNG in diesel engines. One such invention has a
coaxial injection of CNG and diesel fuel into the cylinder
combustion chamber of the engine. However, the injector utilized
for the coaxial injection is technically complex. Furthermore,
injectors, which have been brought forth previously for coaxial
injection of CNG and diesel fuel, have been very expensive.
It is desirable to provide a diesel engine that can be powered by a
mixture of CNG and liquid diesel fuel. It is also desirable to
provide a multi-fuel diesel engine which has a less complex design
for its injector units. It is furthermore desirable to provide a
multi-fuel diesel engine as described wherein the injectors are
less expensive than those previously provided.
SUMMARY OF THE INVENTION
To make manifest the above delineated and other desires, the
revelation of the present invention is brought forth. The present
invention provides a CNG/diesel liquid fuel internal combustion
engine that uses CNG to bring the diesel fuel out of a dual fuel
injector. The dual fuel injector has a mixing chamber with an
outlet fluidly connected with the combustion chamber via a first
valve. A liquid fuel line is provided for delivering liquid fuel to
the mixing chamber. The liquid fuel line is connected to the mixing
chamber via a second valve. A combustible gas delivery line is also
connected with the mixing chamber to deliver compressed combustible
gas thereto. In operation, the second valve is opened to inject
pressurized liquid fuel into the mixing chamber. Subsequently, the
first valve is opened to allow the CNG to bring the diesel fuel
into the combustion chamber.
Accordingly, mechanical power from the engine is needed only for a
low pressure diesel fuel (feed) pump (<50 bar), in contrast to a
high pressure fuel pump (>200 bar, up to a few thousand bar) for
a conventional diesel engine. Due to the lower power requirement
for driving the diesel fuel pump, fuel economy of the engine is
improved. The lower pressure diesel fuel pump is also less
expensive than the prior required high-pressure diesel fuel feed
pump.
It is a feature of the present invention to provide a dual fuel
compression ignition diesel engine. It is also a feature of the
present invention to provide a dual fuel internal combustion diesel
engine which does not require a high-pressure pump for the diesel
fuel.
The above-noted features of the present invention will become
apparent to those skilled in the art from a review of the invention
as it is provided in the accompanying drawings and detailed
description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a preferred embodiment compression
ignition internal combustion engine of the present invention.
FIGS. 2-4 are views similar to that of FIG. 1 illustrating
alternate preferred embodiments of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 illustrates a compression ignition internal combustion
engine 7 according to the present invention. Compression ignition
internal combustion engines are commonly referred to as diesel
engines. The engine 7 has at least one and typically a plurality of
cylindrical combustion chambers 10. The combustion chamber 10 has
an air inlet 14 and an exhaust outlet 18. Controlling flow through
the air inlet 14 is an inlet valve 22. Controlling flow through the
exhaust outlet 18 is an outlet valve 26. Slidably mounted within
the combustion chamber 10 is a reciprocating piston 30. The piston
30 has a head 32 that is sealed within the combustion chamber 10 by
seal rings 34 and 36. The piston head 32 also has a depression 40
to induce swirl.
The engine 7 has a dual fuel injector 44. The dual fuel injector 44
has a mixing chamber 46. The mixing chamber 46 has an outlet 50
that is fluidly connected with the combustion chamber 10 via a
first valve 54. The first valve 54 is provided for metered atomized
delivery of the contents of the mixing chamber 46 into the
combustion chamber 10. The first valve 54 is typically solenoid
actuated and is similar to an air forced gasoline fuel
injector.
A source of high pressure compressed natural gas (CNG) is provided
as one of the fuels for the engine 7. The original pressure of the
CNG can be up to a few hundred bars. A pressure regulator is
provided to keep the CNG pressure between fifteen and forty-five
bars (preferably between fifteen and thirty bars) in a compressed
combustible gas delivery line 56. Accordingly, the pressure within
the mixing chamber 46 equals the pressure in the compressed
combustible gas delivery line 56.
A second valve 60 is fluidly connected with the mixing chamber 46.
The second valve 60 is typically a solenoid actuated valve. The
second valve 60 is also fluidly connected with a source of
pressurized liquid fuel product. The pressurized liquid fuel
product is typically a diesel fuel which has been pressurized by a
low pressure feed pump. The pressure of the diesel fuel in the
diesel fuel line 64 will typically be in a relatively stable range
of thirty to fifty bars. The pressure of the diesel fuel in the
diesel fuel delivery line 64 is typically selected to always be
greater than the pressure of the CNG in the CNG delivery line 56.
The control of the second valve 60 will typically be electric pulse
width modulation. In similar fashion, the control of the first
valve 54 will also be pulse width modulation.
In operation, from a top dead-center position, the inlet valve 22
is opened allowing air to be drawn into the combustion chamber 10
as the piston 30 is lowered. The exhaust valve 26 remains closed.
At or slightly before bottom dead center, the inlet valve 22 is
closed. The piston 30 is then brought upwards to compress the air
above the cylinder head 32. As previously mentioned, the control of
the compressed natural gas is conducted by the opening and closing
of the first valve 54. Accordingly, the mixing chamber 46 will
normally be filled with the CNG delivered by the delivery line 56.
Liquid diesel fuel is delivered in a metered fashion into the
mixing chamber 46 by the second valve 60. The diesel fuel can enter
the mixing chamber 46 due to its higher pressure. After the entry
of diesel fuel into the mixing chamber 46, the first valve 54 is
opened to deliver the CNG and diesel fuel into the combustion
chamber 10 in a flow stream 58. Upon further compression of the
combustion chamber by the piston 30, the diesel fuel burns first by
auto ignition and then the high temperature flame ignites the CNG.
At high engine load operational conditions, split injection should
be used. The first or initial injection occurs during the intake
stroke of the piston 30. The first injection is made with CNG only.
Accordingly, the first valve 54 will be opened. A second injection
is made as previously described during the compression stroke of
the combined CNG and diesel fuel. If the load upon engine 7 should
decrease, the injection pulse width of the first CNG injection will
be shorted to reduce the total amount of CNG. The initial injection
of CNG will also be retarded to reduce the homogeneity of the fuel
within the combustion chamber 10. At even lighter loads, the first
injection of CNG only can be eliminated. Accordingly, a single
injection during the compression stroke at light loads results in a
stratified fuel distribution within the combustion chamber 10.
Stratified fuel distribution promotes a fast burn. The fuel mass
ratio of CNG to diesel fuel will depend upon operating conditions.
In general, the variation of diesel fuel mass per cycle will
typically be small. The change in engine load is realized mainly be
changing the injected CNG mass per cycle. At full engine loads it
is desirable to control the diesel fuel mass to be less than five
percent of the total fuels. The ratio between diesel fuel and CNG
will increase as the load upon engine 7 decreases.
Referring to FIG. 2 with like items being given similar reference
numerals, an alternative diesel engine 117 according to the present
invention additionally has compressed air injection. The engine 117
has a source of CNG as previously described. Between the source of
CNG and the pressure regulator there is a gas motor. The gas motor
utilizes the pressure in the CNG to power an air compressor. The
air compressor is connected into a compressed air delivery line 80.
The engine 117 has a first valve 54 as previously described. The
engine 117 has a third valve 70 which is typically solenoid
actuated which controls the flow of CNG between CNG delivery line
56 and the mixing chamber 46. Fluidly connected with the mixing
chamber 46 is a fourth valve 88 to meter the amount of compressed
air delivered to the mixing chamber 46. If desired, the air
compressor can be connected with an accumulator or compressed air
storage bottle (not shown). The engine 117 will operate in a
similar fashion as aforedescribed for the engine 7 for multiple
injections. The initial injection of CNG during the intake stroke
is made by opening the first valve 54 and the third valve 70. For
the second injection, the second valve 60 will allow delivery of
pressurized diesel fuel. The fourth valve 88 will be selectively
energized to allow for delivery of compressed air into the mixing
chamber 46 to bring out the diesel fuel into the combustion chamber
10. Bringing out the diesel fuel with the compressed air will
eliminate the fuel rich region that may be created by the second
aforementioned fuel injection at full engine load.
Referring to FIG. 3, the compression ignition internal combustion
engine 217 functions in a manner essentially as described with
regard to the engine 117, with the exception that a separate
driver, typically the engine 217 itself, is used to drive the air
compressor.
FIG. 4 illustrates an embodiment of the present invention wherein
the compressed air is supplied by a compressor or accumulator (not
shown). The third valve 70 and fourth valve 88 have been replaced
by a three-way valve 90 which can be alternatively switched to
connect the mixing chamber 46 with the source of compressed air or
with a source of CNG.
The engines 117, 217 and 317 can also be switched to function in a
manner to bring out the diesel fuel with the CNG as desired by
engine operational parameters. All of the engines 7, 117, 217 and
317 may have an added second high pressure diesel fuel injector to
allow the combustion chamber 10 to be alternatively powered as a
standard diesel engine or powered as a combined fuel CNG/diesel
fuel engine.
The present invention compression ignition engine and methods of
operation thereof have been shown in several embodiments. However,
it is apparent to those skilled in the art that various
modifications can be made to the present invention without
departing from the spirit or scope of the present invention as it
is encompassed in the specification and drawings and by the
following claims.
* * * * *